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By B. M. Larsen, L. S. Darken

Some years ago we collated all laboratory data then available to us on the distribution at equilibrium of manganese and of sulphur between metal and simple slags, and used the results in setting up an equation, which proved to be in accord with determinations of the distribution ratio of manganese and of sulphur between liquid steel and open-hearth slag, over a wide range of operating conditions. We now present an outline of our calculations and inferences on these two closely related questions, which are of especial importance because of the advisability of conserving manganese wherever possible. In general, our results show that in the open-hearth furnace equilibrium between metal and slag, with respect to both manganese and sulphur, is substantially attained during the finishing period of the heat, or in about a half hour to an hour after any additions were made. This implies that the end result will be identical whether manganese is added as alloy or metal to the liquid steel or as oxide to the slag. The proportion of total manganese retained by the steel is favored: (I) by use of the minimum amount of lime, consistent with other operating limitations, required to give a lime-silica ratio of about 2.4, which usually corresponds to a minimum practical slag volume; (2) by a high concentration in the slag of MnO relative to FeO; (3) by high operating temperature. Absorption of sulphur by the slag from the liquid metal is favored: (I) by large slag volume; (2) by a high concentration of active (or "free") lime and of manganese oxide dissolved in the slag; (3) by low concentration of silica, iron oxide, and phosphate dissolved in the slag. Distribution 02 Manganese between Slag and Metal at Equilibrium On the basis that the distribution of manganese between liquid steel and slag is controlled by the reaction FeO + Mn -& MnO + Fe [A] slag metal slag metal the distribution at equilibrium, at a given temperature, is expressed by the equilibrium constant for this reaction, which is defined as K,, _ aMnO' afe aFeO ' aMn where a is the activity of the molecular species denoted by the subscript. The activity of each of the several components, although it is not known precisely, is approximately equal to the concentration of each component expressed as its mol fraction; that is, as the ratio of the number of mols of the given component to the total number of mols of all the molecular species present in the metal or slag, as the case may be. Moreover, since the activity, or concentration, of iron in the liquid metal is in fact substantially constant, the term afe may be combined with K" to give a new constant K'. Making these changes, 7

Jan 1, 1942

By B. M. Larsen, L. S. Darken

Some years ago we collated all laboratory data then available to us on the distribution at equilibrium of manganese and of sulphur between metal and simple slags, and used the results in setting up an equation, which proved to be in accord with determinations of the distribution ratio of manganese and of sulphur between liquid steel and open-hearth slag, over a wide range of operating conditions. We now present an outline of our calculations and inferences on these two closely related questions, which are of especial importance because of the advisability of conserving manganese wherever possible. In general, our results show that in the open-hearth furnace equilibrium between metal and slag, with respect to both manganese and sulphur, is substantially attained during the finishing period of the heat, or in about a half hour to an hour after any additions were made. This implies that the end result will be identical whether manganese is added as alloy or metal to the liquid steel or as oxide to the slag. The proportion of total manganese retained by the steel is favored: (I) by use of the minimum amount of lime, consistent with other operating limitations, required to give a lime-silica ratio of about 2.4, which usually corresponds to a minimum practical slag volume; (2) by a high concentration in the slag of MnO relative to FeO; (3) by high operating temperature. Absorption of sulphur by the slag from the liquid metal is favored: (I) by large slag volume; (2) by a high concentration of active (or "free") lime and of manganese oxide dissolved in the slag; (3) by low concentration of silica, iron oxide, and phosphate dissolved in the slag. Distribution 02 Manganese between Slag and Metal at Equilibrium On the basis that the distribution of manganese between liquid steel and slag is controlled by the reaction FeO + Mn -& MnO + Fe [A] slag metal slag metal the distribution at equilibrium, at a given temperature, is expressed by the equilibrium constant for this reaction, which is defined as K,, _ aMnO' afe aFeO ' aMn where a is the activity of the molecular species denoted by the subscript. The activity of each of the several components, although it is not known precisely, is approximately equal to the concentration of each component expressed as its mol fraction; that is, as the ratio of the number of mols of the given component to the total number of mols of all the molecular species present in the metal or slag, as the case may be. Moreover, since the activity, or concentration, of iron in the liquid metal is in fact substantially constant, the term afe may be combined with K" to give a new constant K'. Making these changes, 7

Jan 1, 1942

By R. J. Stokes

This paper compares the room-temperature mechanical behavior of magnesium oxide crystals containing 'fresh' and 'grown in' sources. 'Fresh' dislocation sources introduced by cleavage or mechanical contact move and multiply to generate slip bands at 3000 psi. Macroscopically the crystals yield smoothly at 6000 psi and can be quite ductile. When 'fresh' sources are eliminated by chemical polishing the crystals have to rely on 'grown in' sources to initiate slip. They then deform elastically up to extremely high stresses (-30 to 50,000 psi) yielding with a sharp stress drop down to the level at which Ifresh' sources operate. Grown in' sources are considered to be associated with impurity wecipitate particles or inclusions. Annealing crystals at 2000°C dissolves these particles thereby eliminating sources for slip. The crystals then become consistently stronger (> 70,000 psi) approaching within 1/10 of the theoretical strength. Dislocations of the grown-in network do not move under stress to nucleate slip. It is proposed that they are locked electrostatically. DISLOCATIONS were originally conceived to resolve the large discrepency between the theoretical and real strength of solids. The idea that slip propagates by the movement of dislocations is now well confirmed both by electron transmission and etch pit studies. But this by itself is not sufficient to explain the low yield strength of crystals for there is still the need to understand where slip dislocations originally come from. Theoretical estimates place the stress to generate dislocations homogeneously in the lattice at approximately 1/30 of the shear modulus,' a value 104 to 105 times greater than the stress at which the very first manifestations of plastic deformation have been observed. Only an special cases can the theoretical strength be approached; in crystals of high perfection such as whiskers2 where dislocation sources do not preexist and in covalent crystals where the dislocations present at room temperature are almost completely immobilized by the bond character of the solid.3,4 For the most part it is necessary to assume that the yield strength of ionic and metallic solids corresponds to the motivation and multiplication of dislocation sources present beforehand. The question as to their origin appeared to be answered by the suggestion of Frank and Read5 that dislocations forming part of the grown-in structure could operate as a mill for the large scale production of dislocations. The Frank-Read mechanism is still widely accepted as the source of dislocations but a number of observations have been reported which are in serious disagreement with it. One of the most intriguing of these is that under normal testing conditions dislocations of the grown-in network appear to play no role in the plastic deformation of rock salt structure ionic solids. This was first reported in the etch pit studies on lithium fluoride by Gilman and Johnston6 and is true also for magnesium oxide. To explain the comparatively low yield stress of lithium fluoride it was proposed by a number of authors7,9 that small unresolved prismatic loops formed by vacancy condensation were acting either directly or indirectly as the dislocation sources. This proposal led Gilman10 to perform a series of detailed and careful experiments on lithium fluoride to try to identify the sources responsible for the initiation of slip. He concluded that prismatic loops played no general role and that other sources were more important. Dislocation sources in ionic crystals can be divided into two general categories. First, there

Jan 1, 1962

By W. Allen

FOR the past six years gravity surveys have been used for underground prospecting in the copper mines at Bisbee, Ariz. The primary purpose of the surveys has been to reduce the diamond drilling and crosscutting necessary for exploration. Since many of the orebodies are small, and geologic control is not always apparent, any information that will direct the drilling and crosscutting is highly desirable. Because of extensive development and exploration work in the copper mines at Bisbee, it has been possible to cover more than 630,000 ft of crosscuts on 30 levels with the gravity surveys. In the process the gravity procedures have been refined to a high degree. Density Contrast: For a gravity survey to be successful, a sufficient density contrast must exist between the geologic feature sought and surrounding host rocks. Most mineralized areas will provide this contrast if fairly massive bodies are present. In the Bisbee area the entire sequence of formations, except for alluvium, appears to have specific gravities ranging from 2.65 to 2.70. These values have been determined by means of a large number of cut samples and diamond drill cores. As a further check, vertical gravity differences have been used where nonmineralized sections are known to occur.' The only known major gravity disturbances result from mineralization that has increased the density and the voids that have decreased density. The voids are caused by mining operations and by underground water movement that has developed several areas of caverns. Equipment: While not absolutely essential, a small rugged gravity meter, such as the Worden meter, is highly desirable. A tall tripod, about the height of a transit tripod, permits instrument set-ups in deep water and in locations where fallen timber and muck piles make it impossible to use a short tripod. An additional advantage of a tall tripod is that it places the meter in the center of the crosscut, reducing the error caused by the crosscut void. Size and weight are important, since the only satisfactory means of operating the meter underground is to carry it by hand. A backpack can be used in rare instances but is usually a hindrance because of the close station spacing. The operator's ability to move through tight clearances will improve survey coverage, as it is then possible to move through raises and caved areas and to pass mine cars and machinery with a minimum of trouble. Station Control: Gravity stations are normally located every 100 ft along the crosscuts, at each intersection, and in the face of all stub crosscuts. In areas of high gravity relief, or where small anomalies might be expected, stations may be located at 25 or 50-ft intervals. When possible, the stations should be offset to avoid effects of raises or other voids. The gravity stations on a level are tied to one or more base stations, which are usually located at the shaft or near the portal of an adit. The base stations may be part of a gravity control net that extends to each level in the mine as well as to the surface. Such a net extending throughout the potential area of the surveys is highly desirable, as it is then possible to compare all gravity stations on a uniform basis. The stations that are part of the base net should be carefully established by multiple readings and, if necessary, by a least squares adjustment of the loops. In some instances where levels do not have a shaft station, or where access may be blocked by caving, it may be necessary to establish secondary bases at the top and bottom of the raises that are between levels. Under fair conditions 70 to 90 gravity stations can be located and run in 6 hr by a two-man crew. The best field procedures depend on conditions. Reduction of Field Data: Most of the time required to produce a final gravity map is consumed in processing the data. Each meter reading must be corrected for a minimum of five factors that affect the gravity value in addition to the density contrast being sought. These factors are 1) instrumental drift, 2) station elevation, 3) topography, 4) latitude, and 5) regional gravity gradient. Mine openings, such as stopes and raises, will affect the value. However, it is seldom practical to make corrections for these voids. Usually a rotation is made on the field note on the station, and any

Jan 1, 1957

By A. H. Bromly

THE small agricultural village of Santa Barbara, in the State of Guanajuato, has been the center of spasmodic tin-mining operations during recent years. The deposits, so far as I know, are unique, and a few brief notes may be of interest. Santa Barbara, about 12 miles west of San Felipe station on the Mexican National Railway, and at an elevation of 2,400 m. above sea-level, is situated in a flat valley extending east and west, and bounded north and south by broken rugged bills rising about 330 m. above the general level of the valley. Tin-mining operations have been conducted-at the Queensland mine, near this village. A small concentrating-mill was erected and attempts were made to smelt the ore in reverberatory furnaces. The country-rock of the district for many miles is rhyolite of great thickness. There are some local variations due to differences in cooling, or subsequent alteration or impregnation; but throughout the whole district the principal constituents of the rocks remain the same, viz., free silica, orthoclase-feldspar and sanidine. The latter is especially marled. The crevice and joints of the rock are frequently filled with calcedonic and opalescent quartz. The ore-formation at the Queensland mine is of an unusual nature, consisting of cracks in the rhyolite which have been filled with clay. This phenomenon is largely developed over a width of from 80 to 100 m., in which the principal fissuring follows an approximate direction of north and south. The av¬erage clip ranges between 70 to 80 degrees. Some of the fissures bold sufficiently true for a time to afford the impression that they are clue to dynamic causes, or earth-movement. This may be true of some of the north by south fissures; but considering

Jul 1, 1905

By PHILIP N. MOORE

THE problem of managing the policies of the Institute so that a middle course may be drawn between the close control of a few who are so situated that they can give continuing attention and intermittent control by occasionally present directors presentation .of the subject is to bring clearly before the membership of the Institute a summary of the attendance at the Directors' meetings for the past four years.

Jan 1, 1924

By H. l. Burghoff, J. S. Porter

This paper presents the results of an investigation of the effect of cold-working and annealing treatments upon the occurrence of preferred orientation in annealed brass wire. The subject has received less consideration than has the same phenomenon in annealed brass sheet or strip, and perhaps very properly so in view of the obvious and undesired results obtained in the forming or drawing of strip having preferred orientation, which results are in contrast with the lack of any spectacular visual evidence in wire. The factors of cold-working and annealing that control preferredness in strip are naturally expected to function similarly in wire. Indeed, one might expect the condition to be commoner in annealed wire, because the severity of the cold-working between anneals in commercial Practice is usually much greater for wire than for strip. For example, a wire that is to be finished in the annealed condition on a diameter of 0.040 in. is commonly subjected to a final reduction of 90 per cent between the last two anneals, the large reduction being accomplished in the successive drafts of a multiple-die machine. Wire for rivets, for instance, on 0.125-in. diameter, although given a slight reduction of about Io per cent after the final anneal, may have been given a prior reduction of 75 to 80 per cent. Barrettl states the fiber axis of annealed 70-30 brass wire to be [111], with some indication of [IOO] as a secondary fiber axis. Croft and Sachs2 have reported briefly on some differences in brass wire with random and with preferred orientations. They showed statistical plots of the twin-band angles with respect to the wire axis or direction of drawing as observed on an axial plane. They also pointed out that the resistance of the wire to corrosion-cracking when externally stressed and exposed to a mercurous nitrate solution decreased as the degree of the preferred orientation increased. Material and PRocedure All the wire for the investigation was processed from one portion as cut for extrusion from a cast billet of the following analysis: 70.13 per cent copper; 0.01 lead; 0.01 iron; 0.02, nickel; 29.83 zinc (by difference). The billet section, 8 in, in diameter, was extruded hot to 3/4-in. diameter, after which it was processed by alternate cold-drawing and annealing treatments as indicated in Fig. I. The earliest anneals in process were at about 1100°F. and the next to the last reductions by drawing were 58 per cent. The diameter of the finally annealed wire was 0.132 in. Semifinal anneals were at 800°F., 950°F. and 1100°F. and reductions of 47.5, 74, 83.5 and 89.5 per cent were employed in drawing to 0.132 in. The final anneals were at 87s°F., 1050°F. and 1250°F. and were

Jan 1, 1944

By H. l. Burghoff, J. S. Porter

This paper presents the results of an investigation of the effect of cold-working and annealing treatments upon the occurrence of preferred orientation in annealed brass wire. The subject has received less consideration than has the same phenomenon in annealed brass sheet or strip, and perhaps very properly so in view of the obvious and undesired results obtained in the forming or drawing of strip having preferred orientation, which results are in contrast with the lack of any spectacular visual evidence in wire. The factors of cold-working and annealing that control preferredness in strip are naturally expected to function similarly in wire. Indeed, one might expect the condition to be commoner in annealed wire, because the severity of the cold-working between anneals in commercial Practice is usually much greater for wire than for strip. For example, a wire that is to be finished in the annealed condition on a diameter of 0.040 in. is commonly subjected to a final reduction of 90 per cent between the last two anneals, the large reduction being accomplished in the successive drafts of a multiple-die machine. Wire for rivets, for instance, on 0.125-in. diameter, although given a slight reduction of about Io per cent after the final anneal, may have been given a prior reduction of 75 to 80 per cent. Barrettl states the fiber axis of annealed 70-30 brass wire to be [111], with some indication of [IOO] as a secondary fiber axis. Croft and Sachs2 have reported briefly on some differences in brass wire with random and with preferred orientations. They showed statistical plots of the twin-band angles with respect to the wire axis or direction of drawing as observed on an axial plane. They also pointed out that the resistance of the wire to corrosion-cracking when externally stressed and exposed to a mercurous nitrate solution decreased as the degree of the preferred orientation increased. Material and PRocedure All the wire for the investigation was processed from one portion as cut for extrusion from a cast billet of the following analysis: 70.13 per cent copper; 0.01 lead; 0.01 iron; 0.02, nickel; 29.83 zinc (by difference). The billet section, 8 in, in diameter, was extruded hot to 3/4-in. diameter, after which it was processed by alternate cold-drawing and annealing treatments as indicated in Fig. I. The earliest anneals in process were at about 1100°F. and the next to the last reductions by drawing were 58 per cent. The diameter of the finally annealed wire was 0.132 in. Semifinal anneals were at 800°F., 950°F. and 1100°F. and reductions of 47.5, 74, 83.5 and 89.5 per cent were employed in drawing to 0.132 in. The final anneals were at 87s°F., 1050°F. and 1250°F. and were

Jan 1, 1944

By H. A. Deans

A three-parameter mathematical model for one-dimensional flow in porous media is developed. The objective of the model is to predict accurately the longitudinal dispersion associated with the flow of either gases or liquids over a wide range of Reynolds number. A qualitative analysis of the model parameters is given. Published experimental pulse-response curves are compared with results predicted by the model. Several general types of problems are given for which the model can be used. INTRODUCTION The problem of multicomponent single-phase flow through porous media is encountered in the study of petroleum reservoirs, gas chromatographic and ion-exchange columns, industrial fixed-bed con-tacters and elsewhere. These particular examples span the wide range of flow conditions possible; Reynolds numbers of less than l0-4 are not unusual in oil-production problems, while values in excess of 103 are common in large fixed-bed operations. The study of flow-dependent transport phenomena is complicated both by the changes in the character of the flow over this range, and by the irregularity of the flow boundaries inherent to porous media. Dispersion is one of the important phenomena known to depend fundamentally on flow conditions as well as on fluid and medium properties. As used in this paper, the term "dispersion" refers to the observed mixing of fluid elements of different composition which occurs in flow systems. The actual mechanism may be one or more of a number listed below. Only dispersion in the direction of the mean flow (referred to as axial or longitudinal dispersion, or mixing) is considered here, although lateral dispersion arises as part of certain coupled mechanisms. MECHANISMS FOR LONGITUDINAL DISPERSION A number of distinct mechanisms are known3,5,7,8 to contribute to the phenomenon of longitudinal dispersion. The more important of these are as follows. 1. Molecular diffusion in the flow direction. 2. Turbulent (cell) mixing. 3. Lateral transport processes coupled with velocity and/or residence time distributions, including: (a) "Taylor" diffusion caused by the interaction of velocity profiles in individual voids with lateral molecular diffusion; (b) separation and remixing or interdiffusion of streams having different velocities around particles; and (c) the couplipg of gross velocity profiles, caused by viscous instability or inhomogeneous porosity, with lateral dispersion. 4. Finite mass-transfer rate between a porous matrix and the flowing phase, and finite diffusion rate inside elements of the porous matrix. It is a well documented fact that these mechanisms, whether acting individually or in combinations, produce essentially similar integral effects. The observed dispersion can be described approximately by solutions of the diffusion equation with a properly chosen dispersion coefficient. Necessary conditions for equivalence between dispersion and diffusion are discussed by Klinkenberg and Sjenitzer.7 Apparently these conditions are not satisfied exactly in many real systems. "Best fit" solutions of the diffusion equation often depart appreciably from measured breakthrough curves for the usual pulse- or step-forced experimental systems. In particular, pulse response curves usually show some degree of asymmetry and "tailing" which cannot be reproduced by the one-parameter diffusion model. The three-parameter model proposed herein attempts to produce these effects in a realistic manner. Asymmetry and tailing are predicted for certain sets of parameter values, while for other sets the new model agrees with the diffusion model. VELOCITY DEPENDENCE OF DISPERSION Molecular diffusion apparently controls at sufficiently low Reynolds number in both gas and liquid systems.*l3 At Re > 20, turbulent cell mixing is dominant for gases flowing at low pressure; the data of McHenry and Wilhelm8 show that the mixing cell is approximately 1 particle diameter long in random sphere packs. on the other hand, the data

By Charles Shamel

I FEAR most of the Institute members are already weary of the perennial controversy about the apex law. I feel that way about it myself now, though I have been guilty of considerable contribution to the discussion in the past. The discussion does not seem to perceptibly influence previously held views and I would not again break into print on the subject but for the urgent invitation of the Chairman of our, Law Committee. This energetic and able member has firmly determined to secure a revision of the mining law and among other things to eliminate the so-called apex provision from the U. S. mining statutes. He is, however, fair about it and has invited me to make "the strongest possible argument in its favor." I am suspicious that he is acting on the psychological principle that it is usually easier to convince an audience against a cause vigorously but unsuccessfully defended than against one wholly mute. Nevertheless, I realize that personally he wishes me no harm, much as he hates the apex law, and so am willing that the Institute have whatever benefit may accrue from my taking up again the unpopular side of the discussion. I say this because the attitude of a large part of our "articulate" membership seems irreconcilably hostile; their minds are made up; favorable consideration is foreclosed; and they become impatient and even sarcastic at any attempt to elucidate a favorable view of the apex law. The exact question for discussion at the present time is not whether on abstract, or any other considerations, the apex law is the best possible rule, but the very different proposition whether, after nearly 50 years of statutory life and much longer as a practically universal miners' custom, it is now just and expedient to repeal the apex law.

Jan 4, 1914

MRS. SIDNEY J. JENNINGS, President MRS. ARTHUR S. DWIGHT, First Vice-President MRS. KARL EILERS, Second Vice-President MRS. H. W. HARDINGE, Third Vice-President MRS. BRADLEY STOUGHTON, Recording Secretary MRS. AXEL 0. IHLSENG, Corresponding Secretary MRS. HARRIS K. MASTERS, Treasurer Welfare Committee MRS. C. C, BURGER, Chairman Sub-Committees Americanization Belgian Relief MRS. LEVI HOLBROOK, Chairman MRS. HENRY H. KNOX, Chairman Emergency MRS. HERMAN A. PROSSER, Chairman A very successful meeting Of the Council of the Woman's Auxiliary was held Wednesday, July 18, and plans for war relief work were thoroughly discussed. The Belgian Relief Committee has sent out the following letter to the ten local sub-committees, which were formed to raise money to feed the Belgian children: "The Commission for Relief in Belgium announced in a letter from Mr. Hoover that after the first of June the United States Government would take over the relief of Belgium and Northern France and called attention to the following paragraph: ?Naturally, having built up such an effective organization you will desire to keep it alive as far as possible, and we venture to suggest that, although the general relief of the countries involved will now be met by the Government appropriations, emer-gencies and special conditions may arise which could only be met by private donations. In such circumstances your organization will afford a ready means of meeting the demands of the situation, whatever they may be. Should any of your contributors

Jan 9, 1917

By O. L. Culberson, J. J. McKetta

INTRODUCTION The equilibrium constants for methane and for water, and for ethane and water have been calculated from experimental data for the two binary systems.2,3,11,12 These constants are for the two-phase systems for the temperature range of 100" to 340°F and the pressure range of 200 to 10,000 psia. The constants for ethane are greater than those for methane. Equilibrium constants for a natural gas from a natural gas-water system6 are about the same as those for methane. Equilibrium constants for water in all three systems are very nearly the same over the greater part of the range of temperatures and pressures studied. In ideal solutions, the vapor-liquid equilibrium constants for a component should be the same in all such solutions at a given temperature and pressure.5 Few solutions are ideal, and consequently the use of generalized constants often leads to error in situations where they do not actually apply. In decidedly non-ideal systems, it is desirable to have equilibrium constant data for the specific system. Vaporization equilibrium constants may be calculated either by thermodynamic methods or from experimental vapor-liquid equilibrium data. In the thermodynamic calculation. the equilibrium constant K may be shown to be" K = fP,/fl'..........(1) where fPi is the fugacity of the pure component i at the given temperature and at the vapor pressure of the pure component, and fp is the fugacity of pure i in the gaseous state at the temperature and total pressure of the system. At best the thermodynamic calculation results in a K applicable to ideal solutions. Equilibrium constants calculated from Equation (1) have been found to have only limited agreement with experimental values, even though the solutions for which they were calculated approached ideality."'" If the more volatile component is at a temperature above its critical, the accuracy of the equilibrium constant for the component is made more doubtful by the use of the vapor pressure term under such conditions. In order to make the thermodynamic calculation on a component above its critical temperature, one must resort to one of the empirical methods of extrapolation of the vapor pressure to conditions above its critical point.13 Application of the thermodynamic equilibrium constant then to the methane-water or the ethane-water systems would be risky since the systems are non-ideal, and the methane and ethane are above their critical in most petroleum operations. ETHANE-WATER SYSTEM In the temperature range of from 100° to 340°F and for pressures up to 10,000 psia, the vapor-liquid equilibrium data 'References given at end of paper. Manuscript received in the office of the Petroleum Branch March 16, 1951.

Jan 1, 1951

By J. J. McKetta, O. L. Culberson

INTRODUCTION The equilibrium constants for methane and for water, and for ethane and water have been calculated from experimental data for the two binary systems.2,3,11,12 These constants are for the two-phase systems for the temperature range of 100" to 340°F and the pressure range of 200 to 10,000 psia. The constants for ethane are greater than those for methane. Equilibrium constants for a natural gas from a natural gas-water system6 are about the same as those for methane. Equilibrium constants for water in all three systems are very nearly the same over the greater part of the range of temperatures and pressures studied. In ideal solutions, the vapor-liquid equilibrium constants for a component should be the same in all such solutions at a given temperature and pressure.5 Few solutions are ideal, and consequently the use of generalized constants often leads to error in situations where they do not actually apply. In decidedly non-ideal systems, it is desirable to have equilibrium constant data for the specific system. Vaporization equilibrium constants may be calculated either by thermodynamic methods or from experimental vapor-liquid equilibrium data. In the thermodynamic calculation. the equilibrium constant K may be shown to be" K = fP,/fl'..........(1) where fPi is the fugacity of the pure component i at the given temperature and at the vapor pressure of the pure component, and fp is the fugacity of pure i in the gaseous state at the temperature and total pressure of the system. At best the thermodynamic calculation results in a K applicable to ideal solutions. Equilibrium constants calculated from Equation (1) have been found to have only limited agreement with experimental values, even though the solutions for which they were calculated approached ideality."'" If the more volatile component is at a temperature above its critical, the accuracy of the equilibrium constant for the component is made more doubtful by the use of the vapor pressure term under such conditions. In order to make the thermodynamic calculation on a component above its critical temperature, one must resort to one of the empirical methods of extrapolation of the vapor pressure to conditions above its critical point.13 Application of the thermodynamic equilibrium constant then to the methane-water or the ethane-water systems would be risky since the systems are non-ideal, and the methane and ethane are above their critical in most petroleum operations. ETHANE-WATER SYSTEM In the temperature range of from 100° to 340°F and for pressures up to 10,000 psia, the vapor-liquid equilibrium data 'References given at end of paper. Manuscript received in the office of the Petroleum Branch March 16, 1951.

Jan 1, 1951

By Chester B. White

ARGENTINA is a country that has never been properly prospected. This is my settled conclusion after reporting on mines in this country ever since 1914, crossing all the mining provinces from Chubut, in the South, to the territory of Los Andes, in the North, chiefly on muleback. It is difficult and costly to get from one district to another. Apart from petroleum, some mineral discoveries have been made but they have been the result of casual rather than systematic work. In Neuquen, Mendoza, San Juan, Cordoba, La Rioja, Catamarca, and Los Andes attempts at mine development have resulted in failures, involving in each instance several million pesos.

Jan 1, 1937

By E. O. Jones, E. Whitehead

During the heating of cold-worked nickel silver, the tendcncy of the material to crack is well known. The present research deals with this question, and may conveniently be divided into the following sections: Changes in these alloys during heating and cooling, determination of the temperature at which cracking occurs, effect of grain size, quenching cracks, methods of overcoming annealing cracking. The work is far from complete, in particular the influence of impurities on this tendency has not been investigated, but the results so far obtained lead to certain definite conclusions, which are of theoretical and practical importance. Changes in Alloys During Heating and Cooling During the annealing of many metals at a temperature just below that at which recrystallization sets in, there is evidence of some change, the effect of which is to harden and embrittle the material. This effect has been most clearly demonstrated in the cases of aluminum, copper, brass, and nickel silver, and appears to be a common property of cold-worked metals and alloys, or, at any rate, the non-ferrous ones. The effect would obviously offer an explanation for certain types of annealing cracking, but the trouble is so much more common in the nickel silvers than in the other alloys that some special cause should be looked for. There is, however, fairly good reason for believing that similar cracking may occur in some of the brasses; D. Bunting1 suggests that the a brasses toward the saturation limit are subject to a transformation closely allied in nature to that known to occur in the nickel silvers at around 320" C. Although the existence of this critical temperature range was known, it did not necessarily follow that this transformation was responsible for the trouble under investigation, so the first portion of this paper deals with the attempts made to determine whether other critical changes might not occur in these alloys. There were already reasons for the belief that such would prove to be the case, as the mechanical properties of the nickel

Jan 1, 1926

By Norman Pilling

The deleterious effect on the mechanical properties of copper, resulting from heating in contact with reducing gases, is well known, but the mechanism of the action does not appear to have been definitely established. The purpose of the present investigation was not to determine the exact variations in physical quality of commercial copper, with its various impurities, as dependent upon the composition of the gas, temperature of exposure, etc., but rather to study the nature of the action and the conditions under which it occurs. The physical result of the so-called "gassing." of copper has been generally described as the development of "brittleness." There appears to be a striking decrease in tensile strength, associated with a considerable loss of ductility, and a small copper strip or wire affected in this way can he snapped in two when bent. Larger articles may have an outer layer alone affected, which can be detached from the core by hammering or bending. Perhaps the earliest reference to this subject is that of Heyn1 in 1900, and among the later observers may be mentioned Archbutt,2 Bengough and Hill,3 Johnson,4 Mathewson and Thalheimer,5 and Ruder .6 Bengough and Hill, while working with arsenical copper, were the first to suggest the possibility of the formation of gases within the copper itself, while Ruder endeavored to explain the action by the reduction of the

Jan 10, 1918

By Irving M. Symonds

COMPAÑIA Minera de Peñoles, S. A., at its Avalos unit operates a lead-zinc concentrator having a capacity of about 600 short tons per day. Lead and zinc concentrates are made by flotation methods. The concentrator is at Terminal de Providencia, in the state of Zacatecas, some 70 miles south of Saltillo, Coahuila. The Peñoles-Avalos railroad operating between the plant and Estacion Avalos, a distance of 6 miles, makes connections with the Coahuila and Zacatecas railroad, which in turn connects with the Nacionales de Mexico at Saltillo. The three railroads are each of different gauge, requiring the transfer of all supplies and concentrates at each junction. The mill operates on company ores, on ores from leased mines, and as a custom mill. The custom business is very small. The lead concentrates are shipped to company smelters at Monterrey, Nuevo Leon and Torreón, Coahuila. Since the European war, all zinc concentrates have been shipped to the United States. ORE TREATED The major source of ore supply is a group of four mines owned or leased by the company, some three miles south of the mill in the mountains, from which the ore is delivered to the mill by a gravity aerial tramway. Custom ore comes in by rail. The ores occur in chimneys. The upper levels contained oxidized siliceous ores of lead, copper, silver and gold, with varying amounts of zinc. These ores were direct-smelted. In the first two years of operation a good deal of the tailing loss was caused by the oxidized content of the ores milled. Much of the ore in the transition zones between the oxides and sulphides was not mined. The ores now being milled are clean, hard sulphides in a limestone gangue, with only occasional contamination of oxides. The lead and zinc sulphides are of coarse structure and are freed even above flotation sizes. The galena is usually "steel" colored, easily and quickly floated. When there is any oxidation, it is usually on the coarsest crystals. The zinc minerals vary a good deal in color; a resin sphalerite predominates but there are varying shades of brown marmatites. On an average, the zinc sulphides contain 64 per cent zinc. The only common copper mineral is chalcopyrite. Little is known of the occurrence of gold and silver. Waste minerals are mainly limestone and pyrite, both of which are barren. The ores vary from 20 to 35 per cent pyrite. Mill heads for the year 1940 and the first eight months of 1941 are given in Table I. [ ]

Jan 1, 1942

By Mark N. Alling

A few years ago, gravel mining in the ancient river beds of Sierra county was the principal industry of the county. Operating drift mines were very numerous and many large hydraulic mines were in action. Eventually the State laws put an end to hydraulic mining, it being claimed that the silt carried down the streams to the valleys filled the rivers and caused winter floods, which were damaging to the surrounding farms. The ancient river deposits which could easily be found were, in the course of 40 years, worked out or practically so. The prohibition of hydraulic mining was a severe blow to the industry in general. The deposits were not developed and the gravel-mining industry practically stood still for many years. In Sierra county, nearly all the hydraulic mines were at the points where the ancient channels were exposed to view by reason of the modern stream erosion, or, in the miner's language, where the channels "enter" or "break out of" the ridges. The claims covering them also covered large areas in which were long segments of lava-capped channels, suitable for drift mines, and the points being hydraulicked were usually the controlling points of attack. Men who have followed hydraulic mining for any length of time seldom are content to work a drift mine. Knowing the great value of their deposits and feeling that they had been robbed by the State, these men have stubbornly held to their claims. The gold that is carried in these gravel channel deposits is more or less scattered throughout the depth and width of the deposit; the percentage that can be recovered by the process of drifting ranges from 50 to 75 per cent. of the total. In hydraulicking, practically all of the deposit is put through the sluices, and as the cost per cubic yard is only about 10 per cent. of the cost of drifting, the deposits, if classed as hydraulic mines, are much more valuable than if classed as drift mines; hence the old timers have held their claims (now worthless as hydraulic mines) at prices which the drift-mining industry could not stand; and such mines

Jan 1, 1915

By William A. Johnson

THE fundamental role of diffusion in many reactions occurring in solid metals has long been recognized, and there have been careful measurements of rates of diffusion in numerous alloy systems, but our understanding of the atomic mechanism by which diffusion occurs is scarcely in an advanced state 1-3 It is doubtful that this mechanism can ever he directly ascertained, rather, all imaginable mechanisms must be examined and the one that is in best accord with such data as can be obtained from suitably chosen experiments should be selected Because of its relative simplicity, diffusion in a system containing only one kind of atomic species-commonly called self-diffusion-is of considerable theoretical interest It may be expected that diffusion theory will not be advanced appreciably until a wide variety of diffusion experiments-of which diffusion in a chemical concentration gradient and self-diffusion are two important types-are carefully performed and inter-compared Aside from the purely theoretical interest in self-diffusion measurements, such studies will be of considerable engineering importance The rate of any process in a pure metal requiring the movement of atoms, of which recrystallization and creep are two familiar examples, will be understood more readily with the aid of self-diffusion data † Self-diffusion implies the diffusion of something into its exact counterpart, the detection of such a process is patently impossible, and it is-necessary to substitute for it the diffusion of one isotope (in this case radioactive) into another isotope (in this case stable) of the same chemical element There is, however, no reason to suppose that a radioactive atom will not diffuse at the same rate as its stable isotope, for all of the isotopes of the same element have exactly the same chemical properties, neither the difference in nuclear energy nor the difference in mass would be expected to exercise an important influence in this phenomenon In this sense, self-diffusion may be thought of as the diffusion of radioactive atoms down a radioactivity concentration gradient, just as usual diffusion is the diffusion of one kind of atone down its chemical concentration gradient The first measurements of self-diffusion ii ere made by von Hevesy4-6 using the radioactive lead isotope thorium B in ordinary lead The recent development of means for producing artificial radioactive elements has made possible similar measurements on gold,7,8 copper,2,9 and zinc 10 11 Many of the data that have been obtained are rather poor, and no adequate reason has been given for their poorness, it appears, however, that the unsatisfactory results are characteristic of the particular experimental procedure employed, and not of self-diffusion measurements in themselves The experimental technique that has yielded the poorer results is the deposition of a thin layer of radioactive atoms on the surface of a specimen and the determination of the rate of inward diffusion

Jan 1, 1941

By J. H. Rushton, L. H. Mahony

Principles of fluid motion and turbulence which have been found to be of use in mixing and agitation problems are discussed, as well as suggested applications in extractive-metallurgy processes. Various types of impellers are described, together with other conditions that affect flow pattern and turbulence. The choice of equipment for particular requirements is considered, and equations for power input are given. Modern heavy-duty mixing and agitation equipment can take an increasingly important part in such extractive-metallurgy processes as solids handling, crystallizing and leaching, chemical operations, and flotation. Application of mixing and fluid-mechanics principles to extraction methods can lead to greater process rates and a resultant saving in time and money. MIXERS are being applied with increasing frequency to problems in the metallurgical industries. The increase represents in part the modernization of mechanical equipment used through the application of unitized drives, modern electric motors and speed reducers, and recently developed materials of construction. Some applications have resulted from process changes and the use of techniques for operations similar to those that have been demonstrated and proven in the chemical industry. Still more applications are being developed through the use of fluid-dynamics principles not previously recognized as applicable to these operations. It is the purpose of this paper to describe those principles of fluid motion and turbulence which have been found to be of use in mixing and agitation problems, and to suggest applications for them in the extractive-metallurgy processes. Modern mixing equipment has been designed to provide the fluid motion consistent with that best suited to different operations.' When properly applied, these more efficient fluid-handling mixers result in lower process-production costs. Metallurgical operations usually involve large amounts of solids. The characteristics of the ore control the process and only enough liquid is added to provide sufficient fluidity for handling and processing. The reactive part of the ore, the mineral value to be extracted, is likely to be low in percentage, and the quantity of reagent required is similarly low, but excessive dilution makes additional reagent necessary and therefore is undesirable. Thus, the primary problems in minerals processing are to handle as high a concentration of solids as possible and to distribute reagents uniformly. These pulps, or slurries, are in a range of solids concentration where hindered settling rates apply, and care must be taken to agitate and mix sufficiently to maintain suspension and flow throughout the equipment. Such slurries have high densities which are the weighted average of the components and viscosities that are spoken of as "effective viscosities" but are difficult to evaluate. It is convenient to separate metallurgical operations involving mixers and agitators into three categories: solids handling, mechanical or physical operations, and chemical operations. In each of these categories fluid motion is required to maintain suspension, to distribute surface-active agents, to blend components and reactants, and to induce high rates of chemical reaction. After a discussion of some basic principles of mixing and agitation, examples of application to the three categories will follow. Fluid Motion The fundamental problems of mixing and agitation of liquids have to do with the mechanics of fluid streams and the means by which they are

Jan 1, 1955